Method and system for operating fluid logic devices

ABSTRACT

A bistable pure fluid jet logic device is operated at low primary flow levels for efficiently performing information storage functions including switching and data retention, and is operated at substantially greater primary flow level for generating substantial work output without jeopardizing the information stored.

United States Patent Inventors Meredith A. Hunter Versailles; Richard E. Languell, Lexington, both of Ky.

Appl. No. 838,111

Filed July 1, 1969 Patented Nov. 30, 1971 Assignee International Business Machines Corporation Armonk, N.Y.

METHOD AND SYSTEM FOR OPERATING FLUID LOGIC DEVICES 13 Claims, 3 Drawing F188.

us. c1 137/2, 137/8 1.5 1.11.01 F151: 1/10, Fl 7d 3/00 Field of Search ..137/s1.5.1.

{56] References Cited UNITED STATES PATENTS 3,199,781 8/1965 Welsh 235/201 3,193,197 7/1965 Bauer 137/81.5 X 3,276,689 10/1966 Freeman 137/81.5 X 3,313,313 4/1967 Katz 137/81.5 3,327,725 6/1967 Hatch, .lr.. 137/81.5 3,420,254 1/1969 Machmer 137/81.5 3,427,962 2/1969 Giannuzzi et a1. 137/81.5 X 3,465,772 /1969 Monge et a1. l37/8l.5 3,472,259 10/1969 Hatch, Jr. et al 137/8l.5

Primary Examiner- Samuel Scott Auorneyx-l-lanitin and Jancin and E. Ronald Coffman ABSTRACT: A bistable pure fluid jet logic device is operated at low primary flow levels for efficiently performing information storage functions including switching and data retention, and is operated at substantially greater primary flow level for generating substantial work output without jeopardizing the information stored. I

PATENTEB 30 I971 3.623.493

45 20 23 55 L 12 f M 53 T\34 32 43 15 H 13 2i INVENTORSE MEREDITH A. HUNTER RICHARD E. LANGUELL av /3 M W ATTORNEY.

METHOD AND SYSTEM FOR OPERATING FLUID LOGIC DEVICES BACKGROUND OF THE INVENTION This invention relates to pure fluid jet logic devices of the type having a primary inlet and a pair of primary outlets diverging to fonn a Y-shaped configuration designed to conduct stable flow from the inlet selectively exclusively to either one or the other primary outlet. Devices of this class are provided with signal input means usually positioned adjacent the intersection of the Y for selecting which of the two primary outlets the flow passes through. Once a primary outlet is selected, flow therethrough is retained without continuance of the selecting signal until a different selecting signal is received.

DESCRIPTION OF THE PRIOR ART It has been known that by appropriate design, a pure fluid jet logic device can be made to operate with a primary flow rate selected from a range of magnitudes. An example of one such design is found in US. Pat. No. 3,283,767. The ability of such a device to operate at any of a number of different primary flow rates has been recognized as an advantage in designing a system where it is necessary to interrnatch the performance of a number of different elements. Accordingly, it is desirable that the perfonnance characteristics of the elements be tolerant to a wide range of operating conditions. Devices within a system once designed, however, are operated at a single nominal power flow rate. Another known advantage of fluid devices designed to accommodate a wide range of flow rates has been the fundamental reliability of devices operating at their lower flow threshold of stability where a disturbance in the fluid source could cause unreliable storage operation.

It is also been known to operate pure fluid jet logic devices by combining selective flow in the primary jet stream as well as selectively flow in the inlet to produce an AND" function. An example of this application is found in US. Pat. No. 3,221,990. It can be recognized that simultaneous flow in both the primary inlet and a given control inlet will produce flow in one of the primary outlets whereas the absence of flow in either the primary inlet or the control inlet will prevent such an output flow. Operation of the device of this class require continuous simultaneous operation of both the power and input flows.

SUMMARY OF THE INVENTION Our invention provides a method and system for operating a multistable fluid logic device or amplifier of the type described so as to maximize switching speed, minimize fluid consumption, and maximize amplification gain all without greatly increasing system complexity or adversely affecting system reliability.

In our invention the fluid logic device is operated when perfonning storage and switching functions at a flow rate that is relatively low but adequate to maintain reliable stable exclusive outlet flow operation. The low flow rate may well be so small as to be incapable of performing any significant useful work and, the the device were operated continuously in this mode would require a further power amplifier of some sort. At a low flow rate the time and energy required to divert the primary jet flow from one primary outlet to the other are both minimized and data entry is therefore accomplished relatively efficiently. Retention of the data thus entered is accomplished reliably but with a minimum of consumption of fluid due to the low flow rate.

When it is desired to read the data thus stored, the primary jet flow rate is increased substantially to a level capable of performing useful work without further amplification. We have discovered that the flow significantly and rapidly increased or decreased without jeopardizing the data stored. The effective amplification gain of the device thus is the ratio of the relatively high flow primary jet generated during readout as compared to the relatively low level input signal required to switch the low level primary jet flow.

Where fluid logic devices are employed to perform complex functions such as repeated additions or subtractions, our invention can be employed to advantage by operating fast during the time-consuming logic operations. These operations might cause a single logic device to be switched between states many times before a sensible output is desired. When the computation is complete, a high flow rate is supplied to read" the result from the system.

Minimization of flow consumption is quite significant in several respects. The rate of flow consumption determines the size of fluid source and storage capability for any given system and thus is a factor of direct cost. Also, the volume of air circulated through a system during its useful life will produce some proportional amount of dirt that will tend to clog the system. The volume of air flow through a system also can be directly related to the acoustical noise generated which may be of prime concern where a device is used in relatively quiet working areas.

Complex information-handling systems often operated by selectively performing their various functions in a relatively rigid time schedule or sequence. Our invention can be employed to make sequence time a variable along with substantive data. Devices conventionally tenned AND gates" are provided to combine a particular bit of data-significant information with a time-sequence bit of information to cause a desired selective function to occur at a specific time. This function could be performed by combining a time base or clock signal applied as a selective primary flow, and the information data applied to a control input as taught in the aforesaid US. Pat. No. 3,22l,990 or it could be performed by providing partial plural input control flows requiring multiple inputs to provide sufficient control flow to generate an output. Both of these approaches require that the actual data control signal be maintained until the time designated by the clock signal. In our invention, information data stored during low flow operation is retained without maintenance of the input signal until the high flow occurs at which time a significant output is produced. Our device thus provides a self-storing AND gate.

One mode of our invention employs an asymmetric bistable fluid device the type wherein the power stream seeks one predetermined primary outlet whenever the power stream is first commenced in the absence of control signal. Our invention can provide a single data output with self-erasing by following the high flow data output control with a negative flow that brings the power stream flow temporarily to a level inadequate to maintain bistable operation. Upon resumption of the maintenance flow the information previously stored will have been destroyed and the device reset. This self-erasing function is easily obtained by employing an unvalved positive displacement pump such as a bellows wherein the forward stroke drives fluid through the fluid logic device and the return stroke withdraws fluid therefrom.

For a better understanding of our invention, reference is made to the accompanying drawing of which:

FIG. I is a cross-sectional view of simple apparatus capable of performing the method of our invention,

FIG. 2 is a perspective view of a system of mechanisms wherein our invention is employed,

FIG. 3 is an cross-sectional elevational view like FIG. I but showing modified apparatus for differently performing the method of our invention.

The method of our invention operates in a system 10 including a pure fluid amplifier or logic device 11 having multiple stable states. The device ll shown is bistable and is configured in accordance with well-known principles of design such that primary flow from primary inlet 12 is selectively, exclusively and stabily directed to either of two diverging primary outlets 13 or 14. Selection of the particular outlet is obtained by directionally disturbing the primary flow at the throat 15. For example, the primary flow can be diverted by either supplying an input flow to one of two control signal inputs 16 or 17 or by selectively choking one of the two control signal inputs 16 or 17. Briefly, flow added to input 17 diverts the primary flow from primary inlet 12 toward primary outlet 14. The primary flow will remain diverted even after the signal flow is terminated. The same result would be obtained if signal input 16 had been temporarily choked or closed. An opposite result, i.e., primary flow in outlet 13, would be obtained by temporarily adding flow to signal input 16 or choking of signal input 17.

To illustrate the principles of our method, a load represented by a fluid motor output device such as an expansible bellows 20 is fluidly connected through duct 21 to primary outlet 14. A restricted bypass 22 is indicated on duct 21 in accordance with known design principles to prevent interference of the output load with operation of device 11. The bellows 20 is assembled to do work against a spring 23 upon receiving an adequate pressure or flow from outlet 14. An electrical output switch 24 is positioned to be closed by the bellows 20 when it expands a preset amount in response to a flow in conduit 21 larger than a preset threshold level. A flow less than the threshold level in conduit 21 may move bellows 20 a small amount that is insufficient to operate switch 24.

Primary inlet 12 of device 11 is connected with a source of fluid flow provided by a positive displacement pump 30 having a movable wall 31 that is driven by electric motor 32 through eccentric cam 33. Leftward movement of wall 31 fills the pump 30 with a fluid such as air through inlet valve 34. Rightward movement of wall 31 discharges the air through output 35 into reservoir 40. The pressure in reservoir 40 is sensed by bellows 41 to open motor control switch 42 and terminate operation of pump motor 32 whenever the reservoir pressure exceeds a predetermined limit. It will be appreciated that other more sophisticated systems are within the skill of the art for providing a source of continuously available positive pressure equivalent to that provided by reservoir 40 herein.

Reservoir 40 is continuously connected to primary inlet 12 via restricted conduit 43 and provides a maintenance level of flow therethrough that is below the threshold rate for operating bellows switch 24 but is of sufficient magnitude to ensure bistable operation of the device ll. The primary inlet 12 is also connected to reservoir 40 through power flow conduit 44 that includes a normally closed power control valve 45. The valve 45, when opened by clockwise rotation of control lever 46, operatively supplies a high power flow from reservoir 40 to primary inlet 12. This high flow exceeds the threshold level of bellows switch 24 and thus is adequate to generate a signifcant output by closing switch 24 in the event that primary flow is directed through primary outlet 14.

A typical operating sequence of the system shown in the drawings would be as follows: Beginning in a normal idle state, flow is passing through conduit 43 but not conduit 44. A stable primary flow thus exists in logic device 11 but no output is sensed at output switch 24. If it is desired to register information in device 11 for later reference, a control signal flow can be admitted to either signal input 16 or 17. Flow admitted to input 17 will easily divert the low maintenance flow from primary inlet 12 to outlet 14. The information thus registered in device 11 can be read out or accessed" at any later time simply by opening valve 45 to deliver a large power level flow to primary inlet 12. Since the information registered caused flow in outlet 14, the power flow when effected also follows outlet 14 to drive bellows 20 and close output switch 24. Had the registered information diverted inlet flow to primary outlet 13, opening of valve 45 would cause no effect on bellows 20 or output switch 24.

It can thus be seen how the method of our invention substantially conserves air for both economy and acoustical noise reduction by maintaining only a low flow for information retention during nonoutput periods of operation. it can also be seen that valve 45 operates with a gating function by which the time an input signal is made eflective can be controlled. For example, an output of bellows 20 can be made to occur at a specific time in a system cycle relative to other operations of that system contingent upon a previous input flow to conduit 17. The timing can be accomplished by cam 47 operating in synchronism with the overall system to open power flow control valve 45.

An application of our method to a slightly more complex system is shown in FIG. 2. A common data processing operation involves the conversion of data presented in parallel bit form into a serial bit form. An example of one data serializer may be found in U.S. Pat. No. 3,420,254. In FIG. 2, a data serializer or processing system 50 having six pure fluid bistable devices 51 each capable of storing a single bit of information is shown. The construction of each pure fluid device 51 is substantially like that of device 11 in FIG. 1. A pneumatic-toelectric output transducer 60 is shown as a bellows 61 acting against a spring 62 and is capable of closing an electrical switch 63 when expanded by flow in its supply conduit 64. Switch 63 thus is closed in response to power level flow from any one of the pure fluid devices 51. The upper primary outlet 52 of each device 51 is connected to manifold conduit 64 through individual conduits 53 each having a bypass vent 54 and a one-way check valve 55 therein to provide isolation between the various fluid logic devices. The primary inlet 56 of each logic device 51 is connected through a common manifold 70 and individual one-way check valves 70a to a source of maintenance level flow, not shown. The primary inlets 56 are also connected through one-way check valves 7l to a respective conduit 72 emanating from a pneumatic commutator device 73. Check valves 7] ensure maintenance flow through the logic devices 51 at all times by preventing loss through conduits 72. Each of the conduits 72 is anchored at its left end in a distributor manifold plate 74 and is located along a common circular are defined by the path of a valve opening 75 in a time-sequence control, commutator disk 76. Opening 75 communicated with a plenum or reservoir 77 receiving power level flow through conduit 78 from a source not shown. A shaft 80 is driven by a synchronous motor, not shown, when connected thereto through a clutch 81 upon the operation of an electromagnet 82 to release clutch latch 83 all as described in aforesaid US. Pat. No. 3,420,254. It will thus be seen that during a single revolution of commutator disc 76, valve opening 75 will successively open a path from plenum 77 to each succeeding conduit 72 to thereby supply power level flow to the primary inlets 56 of each succeeding logic device 51. Each of the logic devices 56 will thus be made to perform as part of the overall system within a predetermined time sequence.

Data bits upon which the system 50 operated may be supplied from any suitable source for example, a paper tape reader 90. Reader is connected by pneumatic conduits 9| to the lower signal inputs 57 of each of the logic devices 51. Reader 90 is also connected via wire 93 to electromagnet 82 to initiate a cycle of operation whenever data is present. In operation, data represented by the selective presence or absence of holes in paper tape 94 will cause a corresponding flow or no-flow in signal inputs 57 of respective logic devices 51. As only maintenance flow is supplied to the logic devices 51, the primary flow in those devices receiving a signal at 57 will be diverted to the upper primary outlet 52, but no sensible output at switch 63 will be effected. As commutator port 75 becomes aligned with the left end of each conduit 72, power level flow is supplied to the primary inlet 56 of the respective logic device 51. Those logic devices 51 whose primary flow had been diverted by a signal at their input 57 will deliver the power level flow through their conduits 53 and common conduit 64 to output transducer 60 to close switch 63. The serialized data output from the system 50 thus is presented electrically across electric wires 65 for use by associated mechanism. After valve port 75 has passed the last conduit 72 it becomes aligned with reset conduit 79 to deliver a brief pulse in common to signal inputs 58 of all logic devices 51 in preparation for a subsequent cycle. Rotating shaft 80 is arrested by clutch 81 becoming disengaged due to positioning of its clutch latch 83 by spring 84.

A variation of our method, shown in FIG. 3, provides a selfresetting memory function. A pure fluid bistable amplifier or logic device 100 is provided with primary outlets 101 and 102 configured to be slightly skewed from perfect symmetry. Whenever adequate flow is initially commenced in primary inlet 103, the skewed arrangement or primary outlets 101 and 102 will cause the primary flow to seek the primary outlet 101. An output transducer 104 is connected to outlet 102 in a manner described in the preceding embodiments. The fluid supply to inlet 103 is somewhat changed from that previously described, particularly in the source of power level flow. Maintenance flow is a centrifugal pump 105 which delivers air continuously through restriction 106 to conduit 107. An unvalved recriprocating bellows pump 108 is also connected to conduit 107. Rotation of a cam 109 drives bellows pump 108 against restore spring 110 to rapidly pump air into conduit 107 and thus supply a pulse of power level flow to primary inlet 103 logic device 100. If a signal flow had been delivered to signal input 111 to cause maintenance flow in primary outlet 102, the power level flow from pump 108 would thus be delivered to transducer 104 as described in connection with FIG. 1. Continued rotation of cam 109 next allows spring 110 to restore pump 108 to its expanded condition by withdrawing fluid from conduit 107. This withdrawal of fluid reduces the fluid available for maintenance flow in logic device 100 and thus terminates bistable operation of the device. After pump 108 has been fully restored, the flow in conduit 107 will again separate from the power flow. A system of this type would be useful where a pulse pump device is employed to provide a vantageous to employ the large effective amplification ratio available through the use of our method to eliminate intermediate power amplifiers between the logic device 11 and the power output device or bellows 20, it is recognized that cascaded and combined logic devices, some or all operated in accordance with our method, can be employed to perform complex functions in accordance with fluid logic design techniques known to the prior art.

Having thus described the concepts of our inventive method and a preferred illustrative system for its implementation, we define the subject matter sought to be patented in the following claims.

We claim:

1. A method of operating a multistable fluid device of the type having a primary inlet, at least two diverging primary outlets, and being configured to conduct stable flow selectively exclusively through any one of said primary outlets, and signal input means for selectively diverting primary flow issuing from said primary inlet to one of said primary outlets, wherein the improvement comprises the steps of:

delivering fluid to said primary inlet at relatively low maintenance flow rates capable of maintaining stable selective flow operation of the device,

operating said signal input means temporarily during the continuance of said delivering of maintenance fluid flow to direct said primary flow to one of said primary outlets, and

thereafter during said continuance, initiating delivery of a power flow of fluid to said primary inlet at rates substantially greater than said maintenance flow rates.

2. The method as defined in claim I of operating a multistable fluid device comprising the further step of:

thereafter substantially reducing the flow delivered to said primary inlet to said maintenance flow rates.

3. The method as defined in claim 1 of operating a multistable fluid device wherein:

said power flow is delivered in the form of a pulse.

4. The method as defined in claim 1 of operating a multistable fluid device wherein one of said primary outlets is operatively connected to an output device that is capable of operating only in response to flow in said one outlet exceeding a predetermined threshold level, and wherein:

said maintenance flow rates are less than said threshold level and said power flow rates are in excess of said threshold level.

5. The method as defined in claim 1 of operating a multistable fluid device wherein the device is constructed to inherently direct primary flow through a particular one of said primary outlets upon initiation of primary flow at a rate capable of maintaining stable selective flow and comprising the further step of:

thereafter reducing said minimum rate capable operation of the device.

6. The method as defined in claim 1 of operating a multistable fluid device wherein said fluid device has only two primary outlets.

7. An operating system employing a multistable fluid device having a primary inlet, at least two diverging primary outlets and being constructed to be capable of conducting primary flow from said primary inlet selectively exclusively through any one of said primary outlets, and signal input means for selectively diverting primary flow from said primary inlet to one of said primary outlets comprising the improvement of:

means creating a continuous maintenance flow of fluid at a first rate connected to said primary inlet,

selectively operative means connected to said primary inlet for providing a power flow of fluid thereto to provide a combined flow rate that is at a second rate substantially greater than said first rate, and

means for rendering said power flow providing means operative.

8. An operating system as defined in claim 7 wherein said power flow providing means comprises a fluid pulse generator.

9. An operating system as defined in claim 7 wherein at least one ofsaid primary outlets is connected to a fluid motor.

10. An operating system as defined in claim 7 wherein one of said primary outlets is operatively connected to an output device that is capable of operating only in response to flow in said one outlet exceeding a predetermined threshold level and wherein:

said combined flow rate level.

11. An operating system as defined in claim 7 wherein the system performs a plurality of selective operations within a predetermined time sequence, one of said operations being selected by a power output in one primary outlet of said device, and wherein the improvement further comprises:

time-sequence control means for operating said power flow providing means at a predetennined time in said time sequence.

12. An operating system as defined in claim 7 wherein said device is configured to inherently direct primary flow through a particular one of said primary outlets upon initiation of said primary outlets upon initiation of primary flow at a rate capable of maintaining stable selective flow and wherein said power flow providing means comprises an expansible chamber pump for first adding flow to and subsequently taking flow from said primary inlet.

13. An operating system as defined in claim 7 wherein said device is provided with only two primary outlets.

primary flow to below the of maintaining selective stable than said threshold level and is greater than said threshold 

2. The method as defined in claim 1 of operating a multistable fluid device comprising the further step of: thereafter substantially reducing the flow delivered to said primary inlet to said maintenance flow rates.
 3. The method as defined in claim 1 of operating a multistable fluid device wherein: said power flow is delivered in the form of a pulse.
 4. The method as defined in claim 1 of operating a multistable fluid device wherein one of said primary outlets is operatively connected to an output device that is capable of operating only in response to flow in said one outlet exceeding a predetermined threshold level, and wherein: said maintenance flow rates are less than said threshold level and said power flow rates are in excess of said threshold level.
 5. The method as defined in claim 1 of operating a multistable fluid device wherein the device is constructed to inherently direct primary flow through a particular one of said primary outlets upon initiation of primary flow at a rate capable of maintaining stable selective flow and comprising the further step of: thereafter reducing said primary flow to below the minimum rate capable of maintaining selective stable operation of the device.
 6. The method as defined in claim 1 of operating a multistable fluid device wherein said fluid device has only two primary outlets.
 7. An operating system employing a multistable fluid device having a primary inlet, at least two diverging primary outlets and being constructed to be capable of conducting primary flow from said primary inlet selectively exclusively through any one of said primary outlets, and signal input means for selectively diverting primary flow from said primary inlet to one of said primary outlets comprising the improvement of: means creating a continuous maintenance flow of fluid at a first rate connected to said primary inlet, selectively operative means connected to said primary inlet for providing a power flow of fluid thereto to provide a combined flow rate that is at a second rate subsTantially greater than said first rate, and means for rendering said power flow providing means operative.
 8. An operating system as defined in claim 7 wherein said power flow providing means comprises a fluid pulse generator.
 9. An operating system as defined in claim 7 wherein at least one of said primary outlets is connected to a fluid motor.
 10. An operating system as defined in claim 7 wherein one of said primary outlets is operatively connected to an output device that is capable of operating only in response to flow in said one outlet exceeding a predetermined threshold level and wherein: said first fluid flow rate is less than said threshold level and said combined flow rate is greater than said threshold level.
 11. An operating system as defined in claim 7 wherein the system performs a plurality of selective operations within a predetermined time sequence, one of said operations being selected by a power output in one primary outlet of said device, and wherein the improvement further comprises: time-sequence control means for operating said power flow providing means at a predetermined time in said time sequence.
 12. An operating system as defined in claim 7 wherein said device is configured to inherently direct primary flow through a particular one of said primary outlets upon initiation of said primary outlets upon initiation of primary flow at a rate capable of maintaining stable selective flow and wherein said power flow providing means comprises an expansible chamber pump for first adding flow to and subsequently taking flow from said primary inlet.
 13. An operating system as defined in claim 7 wherein said device is provided with only two primary outlets. 